在MySQL数据库中获取每个团队的最后6条记录 [英] Getting last 6 records for each team in a MySQL database
问题描述
我有一个包含足球比赛结果的MySQL数据库,并且只想检索该数据的特定子集.
I have a MySQL database containing soccer results and want to retrieve just a specific subset of that data.
数据由一个包含MatchDate,HomeTeam,AwayTeam,HomeGoals,AwayGoals的表组成
The data consists of one table containing MatchDate, HomeTeam, AwayTeam, HomeGoals, AwayGoals
我如何检索这些数据的子集,其中包含每个团队参与的最近6场比赛?
How can I retrieve a subset of this data that contains the last 6 matches that each team has been involved in?
虽然我可以为单个团队执行此操作,但是如何获得一个包含表中每个团队的最后6个匹配项的子集? (我不担心该子集可能包含一些重复项.
Whilst I can do this for a single team, how do I get a single subset that contains the last 6 matches for each team in the table? (I am not worried that the subset may contain some duplicates).
推荐答案
这是使用user-defined variable
做到这一点的一种方法:
Here's one way to do it with a user-defined variable
:
select MatchDate, HomeTeam, AwayTeam, HomeGoals, AwayGoals
from (
select
MatchDate, HomeTeam, AwayTeam, HomeGoals, AwayGoals,
@teamCounter:=IF(@prevHome=HomeTeam,@teamCounter+1,1) teamCounter,
@prevHome:=HomeTeam
from yourtable
join (select @teamCounter:=0) t
order by HomeTeam, MatchDate desc
) t
where teamCounter <= 6
这是小提琴的更新:
select team, MatchDate, HomeTeam, AwayTeam, HomeGoals, AwayGoals
from (
select
team, yourtable.MatchDate, HomeTeam, AwayTeam, HomeGoals, AwayGoals,
@teamCounter:=IF(@prevHome=team,@teamCounter+1,1) teamCounter,
@prevHome:=team
from yourtable
join (
select distinct matchdate, hometeam team
from yourtable
union
select distinct matchdate, awayteam
from yourtable
) allgames on yourtable.matchdate = allgames.matchdate
and (yourtable.hometeam = allgames.team or yourtable.awayteam = allgames.team)
join (select @teamCounter:=0) t
order by team, yourtable.MatchDate desc
) t
where teamCounter <= 6
order by team
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